Coded track circuit employing feedback energy



C. W. FAILOR April ll, 1950 CODED TRACK CIRCUIT EMPLOYING FEEDBACK ENERGY Filed March l0, 1949 Charly lkw@ Nv J.

Patented pr. 11, 1950 CODED TRACK CIRCUIT EMPLOYING-FEED- BACK ENERGY' Charles W. Failor, Forest Hills, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application March- 10, 1949, Serial No. 80,658

8 Claims. l

My invention relates to coded track circuits for railroads and particularly to codedA track circuits of the type in which master code energy is normally supplied in one direction over the section rails and feed-back or return code energy is supplied over the section rails in the opposite direction.

In systems of this type. a transmitter relay located at one end of a track section has contacts effective in their first position to connect a code following `approach relay across the rails of the track section, and effective in their second position to connect a source of energy across the. section rails to thereby supply an impulse of master code energy to the section rails.

It has heretofore been proposed to include in the circuit by which the transmitter relay is operated by the code transmitters a back contact of the approach relay to thereby prevent operation ofthe transmitter relay to interrupt the circuit of the approach relay unless the approach relay releases. This prevents improper code following operation of the approach relay in the event foreign current is present in the section with which the approach relay is associated.

Since the transmitter relay cannot be operated to cause an impulse of master code energy to be supplied tol the section rails until' the approach relay releases, any delay in the release of the approach relay may result in a reduction in the length of the impulses of master code energy. Ii these are shortened appreciably the code detecting means governed by the track relay, or incorporated in cab signal equipment on a locomotive in the section, will not operate correctly.

The time required for the approach relayv to release is governed by the length of the associated track circuit and by the level of the charge developed in the ballast of the track section.

A charge is developed in the ballast of a track section as a result of the supply of energy tothe section rails. If this charge builds up to too high a level it will objectionably delay the release of the code `following relays which are operated over the rails of the track section and necessitate a reduction in the length of the track section to prevent objectionable shortening of the master code impulses.

The level of the charge developed in the track ballast increases with increases in the percentage f of the time during whichl energy is supplied to the section rails. When a track circuit is operated by master code energy of 180 code frequency and feed-back energy is supplied over the section rails, energy is supplied. to the section rails for such a large proportion of the time that the charge developed in the track ballast builds up to such a levell that the length of track circuit which can be operated is substantially shorter than that which could otherwise be operated. When a track circuit is operated by master code energy of 75 code frequency and feed-back energy is supplied over the section rails, energy is supplied to the section rails for a substantially smaller proportion of the time and the charge developed in the track ballast is correspondingly reduced with the result that there is a corresponding increase in the length of the track circuit which can be operated.

An object of this invention is to provide an improved coded track circuit of the type described which is arranged so that the charge built up in the track ballast as a result of the supply of energy to the section rails does not limit the length of the track section over which the track cir-cuit may be operated.

Another object of this invention is to provide an improved coded track circuit of the type described' which is arranged so that the approach relay will not distort or interfere with the master code energy.

A further object of the invention is to provide a coded track circuit of the type described which is arranged so that the track circuit is operated by coded energy of low code speed as long as feed-back or return code energy is supplied over the section rails;

Anotherv object of the invention is to provide a coded track circuit of the type described which isA arranged so that the track circuit is operated by codedv energy of high code speed only when the supply of feed-back or return code energy over the section rails' is out off.

A further object of the invention is to provide an improved coded track circuit of the type de"- scribed and arranged to employ master code energy of. standard frequency code pattern.

Other objects of the invention and features of novelty will be apparent from the following description taken in connection with the accompanying drawing.

In practicing my invention, I arrange the crcuit.y for the transmitter relay so that irrespective of traffic conditions in advance, energy of 75 code frequency isv supplied to the transmitter relay as longas feed-'back or return code energy is supplied over the section rails, and so that energy of 180 code frequency may be supplied .f tov the transmitter relay only when the supply of feed-back or return code over the section rails is cut olf.

In the drawing the single iigure is a diagram of a stretch of railway track including a track equipped with a coded track circuit equipment embodying my invention.

Referring to the drawing, there is shown therein a stretch of railway track having track rails I and 2 over which traflic normally moves in the direction indicated by the arrow, that is, from left to right. rThe rails of the track stretch are `divided. by insulated joints 3 into the customary successive track sections. One complete track section designated 5T is shown together with portions of the adjoining sections 6T and 4T.

The equipment at the entrance end of the section includes a code following track relay STR, code detecting relays EFP, 5H, and 5D, a feedback or return code generating relay 5ACR, a decoding transformer SDT, and a battery 51B.

The equipment at the exit end of the section includes a transmitter relay ECTM, a code following approach relay SAR, code detecting relays 5AFP and 5ABP, code transmitters 'l5CT and ltCT, and a track battery 5TB.

The code transmitters 'IECT and lSllCT may be of any suitable construction well-known in the art and are provided with contacts which are operated at rates such as to provide 75 or 180 energy impulses a minute, the impulses being separated by time intervals Which are substantially as long as the energy impulses.

The equipment at each end of the section includes a suitable source of direct current such as a storage battery, not shown, the terminals of which are designated B and C in the drawing.

The equipment at the entrance end of the section includes a relay designated tAFP which is governed in accordance with traffic conditions in section 5T so as to be picked up only when sec- 1-f:

tion @T is vacant and to be released when section 6T is occupied. The means for controlling the relay BAFP is not a part of this invention and this relay may -be controlled in any suitable manner as, for example, in substantially the same manner as the relay '.AFP at the exit end of the section.

The equipment at the exit end of the section includes a relay 4H which is governed by trafc conditions in advance so as to be picked up only when section 4T is vacant and is released when section iT is occupied. The relay 4H may be controlled in any suitable manner well-known in the art as, for example, in substantially the same manner as the relay 5H at the entrance end of the section. The relay lll-I operates at times as hereinafter explained to determine whether the transmitter relay ECTM is operated lby 75 or 180 code frequency, while this relay may also govern the indication displayed by signal 4S.

In like manner, the relay 5H may be employed to control the supply of coded energy to the rails of section GT in addition to being used to control the circuits for the lamps of signal 5S.

The equipment is shown in the condition which it assumes when the track stretch is vacant so that relays 13H and SAFE are picked up. In addition, at this time, as hereinafter explained, the relay SAFP is picked up so that energy is supplied over contact lil of the transmitter relay lSCT, front contact li of relay SAFP, and back contact l2 of the code following approach relay iAR to the winding of the transmitter relay 5CT1VI with the result that its contact I4 is picked up and interrupts the circuit for connecting the winding of the approach relay 5AR across the section rails and establishes a circuit for connecting the track battery ETB across the section rails.

rThe energy supplied from the track battery STB feeds from the positive terminal of the battery over front Contact id of transmitter relay ECTM to track rail i, thence to the left-hand terminal of the winding of the track relay STR, through the relay winding, over front contact i6 of track relay STR to track rail 2, and thence to the negative terminal of the battery. The energy supplied to the winding of relay 5TR keeps the relay contacts picked up so that contact i6 maintains the circuit of relay 5TR and interrupts the circuit including front contact i8 of relay SACR for supplying energy from the battery 51B to the rails of section 5T. 1n addition, as relay ETR is picked up, its contact I9 establishes the circuit including front contact 2D of relay @AFP for supplying energy to the relay 5ACR and its contacts are picked up. Also, as relay ETR is picked up, energy is supplied over its front contact 2l to relay EFP, and the contacts of relay SFP are picked up so that its contact 22 in the circuit for supplying energy to the primary winding of the decoding transformer 5DT is closed, but at this time this circuit is open at contact 23 of relay SAFP. Accordingly, energy is not supplied to the decoding transformer EDT and therefore it is not supplied from this transformer to relay 5D and its contacts are released.

After a short time interval contact lil of the code transmitter lCT is moved to its open position, thereby interrupting the previously traced circuit for supplying energy to the transmitter relay CTM so that its contact lll releases and interrupts the circuit for connecting battery STB across the rails of section 5T and establishes the circuit for connecting the approach relay AR across the section rails. When the supply of energy from the battery STB to the rails of y section 5T is cut off, the track relay TR releases and its contact I9 interrupts the circuit for supplying energy to the relay ACR and connects the left-hand terminal of the winding of this relay to terminal C to thereby short-circuit the relay winding and relay the release of the relay contacts. In addition, the relay EACR is snubbed by a rectifier so that the relay contacts remain picked up for a short time interval subsequent to interruption of the supply of energy to the relay winding.

On movement of contact l5 of relay TR from its picked-up to its released position, the stick circuit for connecting the winding of relay 5TR across the rails of section 5T is interrupted and a circuit is established for connecting the battery 51B across the section rails as long as contact i8 of relay EACR remains picked up.

On release of the contacts of relay ETR, energy is supplied over its back contact 2l and over a front contact of relay 5Fl to the winding of relay 5H so that the contacts of relay 5H are picked up. The windings of the relays 5Fl3 and 5H are snubbed by rectiers which render the relays slow enough in releasing so that contacts of each of these relays remain picked up during the periods in which the supply of energy to the relay winding is interrupted.

The energy supplied from battery 51B feeds over the section rails and over back contact lll of relay SCTM to the winding of relay SAR and picks up its contacts with the result that contact 24 establishes a circuit for supplying energy tothe winding of relay SAFP, while contact l2 of relay SAR interrupts the circuit of relay SCTM to insure that it remains released so that its contact I4 maintains the circuit of relay SAR.

A condenser is connected across the terminals of relay SAFP and is charged during the periods in which energy is supplied to the relay winding while, thisv condenser serves to maintain the relay contacts picked up during the releasedperiods ofthe contacts of relay SAR. The various parts of the equipment are arranged and proportioned so that. the condenser associated with relay SAFP keeps the relay contacts picked up as long as relay SAR is responding to coded energy even though the picked-upy periods of the contacts of this relay are relatively short and the intervals between picked-up periods are relatively long.

As the contacts of relay SAFP are picked up, its contact II in the previously traced circuit for supplying energy of 75 code frequency to the transmitter relay SCTM is closed.

After a short time interval the contacts of relay SACR release and its contact I8 interrupts the circuit for connecting battery SIB across the section rails, while contact I'I of relay SACR establishes the pickup circuit for connecting the winding of relay STR across the rails of section ST.

When the supply of energy from the battery SIB is cut off, the relay SAR releases and its contact 24 interrupts the supply of energy to relay SAFP andV establishes a circuit including a front contact of relay SAFP for supplying energy to the relay SABP. The relay SABP is snubbed by a rectier and is slow enough in releasing to remain picked up during the picked-up periods of the contacts of relay SAR. Accordingly, as long as relay SAR is responding to coded energy, contact 2S of relay SABP is picked up and this contact may control circuits which may be employed in any suitable manner for any appropriate purpose as, for example, to controlV a highway crossing signal orto control the locking of a switch in advance of section ST.

In addition, on release of relay SAR, its back contact I2 in the circuit for supplying energy to transmitter relay SCTM is closed so that energy is supplied to this relay on subsequent movement of contact I of the code transmitter 'ISCT to its closed position.

On the subsequent supply of energy `to the transmitter relay SCTM and movement of its contact I4 to its picked-up position, the circuit of relay SAR is interrupted and the track battery STB is again connectedv across the section rails. The energy supplied from the battery STB ows over the section rails and over front contact I1 of relay SACR to the winding of relay STR. Accordingly, the contacts of relay STR pick up and contact IS of the relay establishes the relay stick circuit to maintain the relay winding connected across the rails of section ST after picking up of contact I'I of relay SACR. In addition, on picking up of the contacts of relay STR, its contact I9 establishes the circuit including contact of relay BAFP for supplying energy to relay SACR and its contacts pick up with, the result that contact I'I interrupts the pick-up circuit for relay STRbut, as explained above, energy continues to be supplied from the section rails to the Winding of relay STR over the relay stick circuit established by frontv contact I6 of the relay. Accordingly,4

the contacts of relay STR remain picked up as long as energy is supplied over the rails of section. ST.

At the end of this period of master code energy the relay SCTM releases to interrupt the circuit of the track battery STB and establish the circuit of the relay SAR, While the track relay STR releases and establishes the previously traced circuit for supplying energy from the battery SIB to the section rails for the release time of the relay SACR. This energy picks up the contacts of relay SAR momentarily to energize relay SAFP while the contacts of relay SAR thereafterrelease so that contact I2 reestablishes the circuit of relay SCTM before contact IU of the code transmitter 'ISCT again moves to its closed position.

Asv long as the stretch is vacant, there-fora the coded track circuit equipment for section ST is operated by coded energy of code frequency and as a result of operation of the track relay STR the relays SFP and SH are picked up, while at this time the relay SD is, released so that the signal 5S, if lighted, will display its yellow or caution indication. In addition, at this time, the relay SACR operates to supply an impulse of feedback or return codey energy from the battery SIB to the rails of section ST following each im pulse of master code energy supplied over the section rails. These impulses of energy supplied from the battery SIB are of suiiicient duration to pick up the relay SAR andto maintain it picked up for an appreciable time interval so that sufficient energy is supplied to relay SAFP and the associated condenser to maintain the relay contacts picked up during the off periods or intervals between impulses of energy from the battery SIB.

When the track circuit of section 5T is operated by coded energy of 75 code frequency, the intervals between successive impulses of master code energy supplied over the section rails are of such length that the approach relay SAR has ample time in which to pick up and release before it is time for another impulse of master code energy to be supplied to the section rails. Furthermore, when the track circuit is operated by energy of 75 code frequency, the level of the` charge built up in the track ballast is suchv that it does not objectionably delay release of the relay SAR. Accordingly, even though transmitter relay SCTM cannot be operated to supply an impulse of energy from the battery STB to the track rails until the relay SAR releases, the impulses of master code energy supplied to the section railsI at this time will not be distorted or reduced in length since the relay SAR will be released and its contact I2 in the circuit of relay SCTM Will be closed before the contact I0 of the code transmitter TSCT completes, this circuit.

If for any reason, foreign current should be present in section ST and should be of .such mag nitude and such polarity as to pick up the contacts of relay SAR, contact I2 of relay SAR will interrupt the circuit of relay SCTM and relay SCTM will be certain to remain released and maintain the circuit for connecting the relay SAR across the section rails so that relay SAR is maintained picked up by the foreign current. Under these conditions, therefore, contact 24 of relay SAR maintains the supply of energy to relay SAFP and its contacts are picked up, but energy is not supplied to relay SABP and its contact 2S is certain to release and interrupt the circuit controlled thereby. Hence, as long as relay SAR is maintained picked up, its contact I2 interrupts the circuit of relay SCTM and there is no danger that contact I4 of relay SCTM will be picked up to interrupt the circuit of relay SAR and thus cause the contacts of relay SAR to release. Under these conditions, therefore, relay SABP is certain to be released and will interrupt the circuit governed thereby, While relay SCTM ceases to supply coded energy to the rails of section 5T and the track relay STR will be released so that relays SFP and SH become released to cause the signal SS, when lighted, to display its red or stop indication.

When the equipment for section 5T is operating in the normal manner, that is, by energy of '75 code frequency, and a train moving in the normal direction of traffic, that is, from left to right, enters section 6T, the relay GAFP releases and its contact interrupts the circuit of relay SACR so that its contacts thereafter remain released and contact I8 interrupts the circuit of relay SIB so that energy is no longer supplied from this battery to the rails of section 5T. After release of relay SACR, its contact I1 continuously maintains the pick-up circuit of relay STR and relay STR continues to respond to master code energy supplied over the section rails.

When the supply of energy from battery SIB to the rails of `section ST is cut off, the relay SAR remains released and its contact 261 no longer establishes the circuit for supplying energy to relay SAFP and after a short time interval the contacts of this relay release so that contact 26 interrupts the circuit for supplying energy to relay SABP and the circuit for connecting the snubbing rectifier across the terminals of the relay winding. Accordingly, the contacts of relay SABP release promptly and contact 2S interrupts the circuit governed by its front contact.

After release of relay SAFP its contact I I transfers the operating circuit for relay SCTM from the wire leading to contact Ill of code transmittel' 'ISCI` and connects this wire to the movable contact 2l of relay 4H so that, if traffic conditions are such that relay III-I is picked up, energy of 180 code frequency will be supplied to the transmitter relay SCTM. Under these conditions, relay SCTM will operate to supply energy of 180 code frequency to the rails of section ST and the track relay STR will be operated at this code speed. Accordingly, relays SFP and SH will be maintained picked up, while at this time energy is supplied over front contact 22 of relay SFP and back contact 23 of relay BAFP to the primary winding of the decoding transformer SDT. As the track relay is assumed to be operating at the 180 code rate the frequency of the energy supplied from the secondary winding of decoding transformer SDT is such that suicient energy is supplied through the resonant rectifier unit IBDU to the relay SD to pick up its contacts. As a result, energy is supplied over back contact 2B of relay SAFP, front contact 29 of relay SH, and front contact 3B of relay SD to the green or clear lamp of signal 5S and this signal displays its proceed indication to the ap proaching train.

At this time the relay SAR is continuously released and its contact I2 in the circuit of the transmitter relay SCTM is continuously closed so that the relay SCTM directly repeats the code transmitter iBUCT. Accordingly, the coded energy supplied to the rails of section ST is not distorted and the impulses are` not reduced in length, as might occur if the approach relay SAR were required to release before the transmitter relay SCTM could operate to cause an impulse of energy to be supplied to the section rails. As the energy of code frequency supplied to the rails of section ST is undistorted, the decoding means including resonant rectifier unit ISGDU and the relay SD associated with the track relay STR operate reliably and the relay SD will be picked up. In addition, if the track section is provided with means, not shown, for supplying coded alternating current energy to the section rails to operate cab signal equipment on locomotives passing through the section, the decoding means on these locomotives will operate reliably.

When the train under consideration advances into section ST the track relay STR remains released and the relays SFP, SH, and SD become released with the result that energy is supplied to the red or stop lamp of the signal 5S.

After entrance of the train into section ST, the supply of energy from the battery SIB over the section rails continues to be prevented and relay SAR remains released and there is no change in the equipment at the exit end of the section.

When the train vacates section ET, the relay GAFP picks up and its contact 28 interrupts the circuits of the lamps of signal SS so that signal is dark, while contact 23 of relay GAFP interrupts the circuit of the primary winding of the decoding transformer SDT and it is deenergized.

When the train under consideration advances into section 15T the relay 4H releases and its contact 2 interrupts the circuit for supplying energy of 180 code frequency to the transmitter relay SCTM and establishes a circuit for supplying energy of 75 code frequency thereto. When the train vacates section ST, the energy of 75 code frequency supplied to the section rails feeds over the section rails and operates the track relay STR to pick up the relays SFP and 5D and to cause relay SACR to operate as previously described so that an impulse of energy is supplied from battery SIB to the section rails after each movement of the contacts of the track relay STR to their released positions. The energy supplied from the battery SIB operates the relay SAR, as previously described and picks up relays SAFP and SABP. As soon as relay SAFP picks up, its contact il interrupts the circuit governed by contact 2l of relay 4H for supplying energy of 75 code frequency to the transmitter relay SCTM and connects relay SCTM directly to the '75 code transmitter so that energy of 75 code frequency is supplied to the relay SC'IM irrespective of the position of the contacts of relay 4H.

When the train advances far enough to vacate section 4T, the relay 4H picks up and the equipment is again in the condition in which it is illustrated in the drawing.

Although I have herein shown and described only one form of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In a coded track circuit, in combination, a section of railroad track having at the rst end thereof a rst source of energy and a rst code following relay having a, contact biased to a released position and having at the second end thereof a second code following relay having a contact biased to a released position, a transmitter `relay having a contact 'movable between a 'across the section rails, means effective on movement of the contact 'of said 'second code following relay from its picked-up to its released position to momentarily connect a 'second Asource of current across the section rails, a slow release relay which is energized when vsaid first code following relay is responding to coded energy, an operating circuit for said transmitter `relay 'effective when established to cause the transmitter relay contact to move from its first toits second position, said operating circuit including a contact of said rst code following relay which is closed only when 'the contacts of said first code following relay are released, means effective when said slow release relay is deenergized for governing said operating 'circuit so as to 'cause said transmitter relay to be operated at times by coded energy of relatively high code speed and at other times by coded energy of relatively low code speed, means effective when said slow release relay is energized for governing said operating circuit so as to cause 'said transmitter relay to be operated only by coded energy of relatively low code speed, and a control circuit governed by means responsive to code following voperation of said first code following relay.

2. In a coded track circuit signaling system, in combination, a stretch of railroad track divided into Aa plurality of track sections including an intermediate track 'section having adjacent the first end thereof a first track section and having adjacent the second end thereof a second track section, said intermediate track section having at the first end thereof a first source of energy and a first code following relay having a contact biased to a released position and having at the second end thereof a second code following relay having a contact biased to a released position, a transmitter relay having a contact movable between a first position Vin which the winding of said first code following relay is effectively connected across the rails of said intermediate section and a second position in which said first source of energy is connected across the rails of said intermediate section, a slow release relay which is energized when said 'first code following relay is responding to coded energy means governed by occupancy of said second track section and effective on movement of the contact of said second code following relay from its picked-up to its released position to momentarily connect a second source of current across the rails of said intermediate section, means selectively responsive to operation of said second code following relay by energy of a low code speed or by energy of a high code speed for controlling entrance of traffic into said intermediate section from said second track section, an operating circuit for said transmitter relay effective when established to cause the transmitter relay Contact to be moved from its first to its second position, said operating circuit including a Contact of said first code following relay which is closed only when the contacts or" said rst code following .relay are released, means governed by trafiic conditions in said first 'track section and effective when said slow release relay is deenergized for governing said operating circuit so as to cause said transmitter relay to be operated at times by coded energy of said high code speed and to be operated at other times by coded energy of said low code speed, means effective when said slow release relay is 'energized for governing said operating circuit so as to cause said transmitter relay to be operated by coded energy of 'a low code speed regardless of traffic conditions in said first track section, and a control circuit governed by means responsive to code following operation of said first code following relay.

3. In a coded track circuit signaling system, in combination, 'a stretch kof railroad track divided into ya plurality of track sections including an intermediate track section having adjacent the first end thereof a first track section and having adjacent the second end thereof a second track section, said intermediate track section having at the first end thereof' a first source of 'energy and a first code following relay having a contact biased to a released position and having at the second end thereof a second code following relay having a contact biased to a released position, a transmitter relay having a contact movable between a first position in which the winding of' said first code following relay is effectively connected across the rails of said intermediate vsection and a second position in which said first source of energy is connected across lthe rails of said intermediate section, a slow release relay which is energized when said first code following relay is responding to coded energy, a signal governing movement yof traffic from said second section into said intermediate section, means effective according as said second code following relay is operated by coded energy of low or of high code speed for causing said signal to display a caution or a clear indication, means governed by traffic conditions in said second track section to momentarily connect a second source of current across the rails of said intermediate section after each movement of the contacts of said second code following relay from their picked-up to their released position, an operating circuit for 'said transmitter relay effective when established to cause the transmitter relay contact to be moved from its first to its second position, said operating circuit including a contact of said first code following relay closed only when the contacts of said first code following relay are released, means effective when said slow .release relay is deenergized for governing said operating 'circuit 'so as to cause said transmitter relay to be operated by coded energy of said high code speed or of said low code speed according as said first track section is vacant or is occupied, 'means effective when said slow release relay is energized for governing said operating circuit so as to cause said transmitter relay to be operated by coded energy of low code speed regardless of tranic conditions in said first track section, and a control circuit governed by means responsive to code following operation of said first code following relay.

4. In a coded track lcircuit signaling system, in combination, a stretch of railroad track divided into a plurality of track sections including an intermediate track section having adjacent the first end thereof a first track section and having adjacent the second end thereof a second track section, said intermediate track section having at the first end thereof a first source of energy and a first code following relay having a contact biased to a released position and having at the second end thereof a second code vfollowing relay having a contact biased to a released position, a transmitter relay having a contact 1l movable between a rst position in which the winding of said first code following relay is effectively connected across the rails of said intermediate section and a second position in which said first source of energy is connected across the rails of said intermediate section, a slow release relay which is energized when said first code following relay is responding to coded energy, a signal governing movement of tralc from said second section into said intermediate section, means effective according as said second code following relay is operated by coded energy of low or of high code speed for causing said signal to display a caution or a clear indication, means effective on movement of the contact of said second code following relay from its picked-up to it released position to momentarily connect a second source of current across the rails of said intermediate section, means responsive to occupancy of said second track section for rendering said last-named means ineffective, an operating circuit for said transmitter relay effective when established to cause the transmitter relay contact to be moved from its first to its second position, said operating circuit including a contact of said first code following relay which is closed only when the contacts of said first code following relay are released, means effective when said slow release relay is deenergized for governing said operating circuit so as to cause said transmitter relay to be operated by coded energy of said high code speed or of said low code speed according as said iirst track section is vacant or is occupied, means effective when said slow release relay is energized for governing said operating circuit so as to cause said transmitter relay to be operated by coded energy of low code speed regardless of traic conditions in said rst track section, and a control circuit governed by means responsive to code following operation of said first code following relay.

5. In a coded track circuit signaling system, in com'bination, a stretch of railroad track divided into a plurality of track sections including a selected track section having a rst track section adjacent the rst end thereof, said selected track section having at the first end thereof a rst source of energy and a iirst code following relay having a contact biased to a released position and having at the second end thereof a second code following relay having a contact biased to a released position, a transmitter relay having a contact movable between a first position in which the winding of said rst code following relay is effectively connected across the rails of said intermediate section and a second position in which said rst source of energy is connected across the rails of said intermediate section, a slow release relay which is energized when said first code following relay is responding to coded energy, means effective on movement of the contact of said second code following relay from its picked-up to its released position to momentarily connect a second source of current across the rails of said selected track section, an operating circuit for said transmitter relay effective when established to cause the transmitter relay contact to move from its iirst to its second position, said operating circuit including a contact of said first code following relay which is closed only when the contacts of said first code following relay are released, means effective when said slow release relay is deenergized for governing said operating circuit so as to cause said transmitter relay to be operated by coded energy of said high code speed or of said low code speed according as said rst track section is vacant or is occupied, means effective when said slow release relay is energized for governing said operating circuit so as to cause said transmitter relay to be operated by coded energy of low code speed regardless of traffic conditions in said first track section, and a control circuit governed by means responsive to code following operation of said rst code following relay.

6. In a code transmitting and receiving means for a coded track circuit, a code following relay having a contact biased to a released position, a source of current, a transmitter relay having contacts movable between a first position in which the winding of said code following relay is effectively connected across the rails of a track section and a second position in which said source of current is connected Iacross said rails, an operating circuit for said transmitter relay effective when established to cause the transmitter relay contacts to move from their first to their second position, said operating circuit including a contact of said code following relay which is closed only when the contacts of said code following relay are released, a slow release relay which is energized in response to code following operation of said code following relay, means effective when said slow release relay is deenergized for governing said operating circuit so as to cause said transmitter relay to be operated by coded energy of high code speed at times and to be operated by energy of low code speed at other times, means effective when said slow release relay is energized for governing said operating circuit so as to cause said transmitter relay to always be operated by coded energy of a low code speed, and a control' circuit governed by means responsive to code following operation of said code following relay.

7. In master code transmitting means and feed back code receiving means for a coded track circuit, in combination, a code following relay having a Contact biased to a released position, a source of current, a transmitter relay having contacts movable between a first position in which the winding of said code following relay is effectively connected across the rails of a track section and a second position in which said source of current is connected across said rails, a slow release relay which is energized in response to code following operation of said code following relay, means effective when said slow release relay is deenergized and including a contact of said code following relay closed only when said code following relay is released for at times operating said transmitter relay by coded energy of high code speed and at other times by coded energy of low code speed, means effective when said slow release relay is energized for always operating said transmitter relay by coded energy of a low code speed, and a control circuit governed by means responsive to code following operation of said code following relay.

8. In master code transmitting means and feed-back code receiving means for a coded track circuit, in combination, a code following relay having a contact biased to a released position, a source of current, a transmitter relay having contacts movable between a rst position in which the winding of said code following relay is effectively connected across the rails of a track section and a second position in which said source of current is connected across said rails, a slow release relay which is energized in response to 13 code following operation of said code following relay, means effective when said slow release relay is deenergized and including a contact of said code following relay closed only when said code following relay is released for at times operating said transmitter relay by coded energy of high code speed, means effective when said slow release relay is released for at other times operating said transmitter relay by coded energy 14 of a low code speed, means effective when said slow release relay is energized for always operating said transmitter relay by coded energy of a low code speed, and a control circuit governed by means responsive to code following operation of said code following relay.

CHARLES W. FAILOR.

N o references cited. 

